1. Field of the Invention
The invention relates to a process for the synthesis of 5-[(substituted)amino]-8-[phenyl or substituted-phenyl]-3H,6H-1,4,5a,8a-tetraazaacenaphthylen-3-ones and to the novel 5-(lower alkyl-thio)-8-[phenyl or substituted-phenyl]-3H,6H,1,4,5a,8a-tetraazaacenaphthylen-3-ones useful as intermediates in the process.
2. Description of the Related Art
The 5-(substituted-amino)-8-(phenyl or substituted-phenyl)-3H,6H-1,4,5a,8a-tetraazaacenaphthylen-3-ones as disclosed in U.S. Pat. No. 4,916,137 possess the ability to enhance neural function in warm-blooded animals affected by behavioral neurological problems, including the cognitive deterioration associated with decreased neural function which occurs with cerebral insufficiency, aging, dementia, and similar conditions. In addition synthetic procedures to prepare the 5-(substituted-amino)-8-(phenyl or substituted-phenyl)-3H,6H-1,4,5a-8a-tetraazaacenaphthylen-3-ones are also disclosed. A series of reactions in which a 4,5-dihydro-7-[phenyl or substituted phenyl]-pyrazolo-[1,5-a]pyrimidine-3-carboxamide is reacted with 1,1,-thiocarbonyl-diimidazole in the presence of sodium hydride to prepare 4,5-dihydro-5-thioxo-8-[phenyl or substituted phenyl]3H,6H-1,4,5a,8a-tetraazaacenaphthylen-3-ones which are subsequently reacted with an amine in the presence of aqueous sodium hydroxide and hydrogen peroxide to give the 5-(substituted-amino)-8-[phenyl or substituted-phenyl]-3H,6H-1,4,5a,8a-tetraazaacenaphthylen-3-ones is disclosed.
It has been found that the 5-(substituted-amino)-8-(phenyl or substituted-phenyl)-3H,6H-1,4,5a,-8a-tetraazaacenaphthylen-3-ones can be advantageously synthesized by reaction of 4,5-dihydro-7-[phenyl or substituted-phenyl]pyrazolo[1,5-a]pyrimidine-3-carboxamide with carbon disulfide in the presence of a lower alkyl iodide and suitable base to give the 5-(lower alkylthio)-8-[phenyl or substituted-phenyl]-3H,6H-1,-4,5a,8a-tetraazaacenaphthylen-3-ones which are subsequently reacted with an amine to afford the 5-[(substituted)amino]-8-[phenyl or substituted-phenyl]-3H,6H-1,4,5a,8a-tetraazaacenaphthylen-3-ones.